Expert System Applications to the Cockpit of the '90s

There is a strong requirement for a new generation of avionics systems with a more integrated hardware and software structure. This integrated avionics system will use significant increases in computer automation with more innovative signal processing, sensor fusion and expert system software to reduce pilot workload, while improving total system performance and reliability. Expert system software packages will be implemented within the core architecture of these next generation integrated avionics systems to assist the pilot. The expert systems will consider the pertinent information available from the ``sensor' subsystems to assess the current situation. The expert systems then consult their knowledge base and rule base software structures to determine alternative reactions to the perceived situation. Then pending upon the critical of the function, situation and reaction, the expert system could either execute the most favorable reaction or display the suggested alternative courses of action to the pilot. This paper addresses the requirement, the enabling technologies and the potential structure of this next generation of avionics. It concludes with two examples of the potential of future avionics expert systems. The two examples are 1) A Navigation and Route Planning Expert and 2) A Threat Assessment and Threat Reaction Expert. Significant things are happening in technology at an accelerating pace that enable the development of this new generation of avionics.     

Phase Space Density Analysis of Energy Transport in the Earth’s Magnetotail

Two energetic events in the Earth’s magnetotail detected by Geotail are examined with detailed analysis of three-dimensional velocity phase space density. It is found that the occurrence of multiple ion components is high during these dynamic episodes. Different populations evolve independently of each other, suggesting particles from multiple activity sites contributing to the observed phase space density. The transport properties with consideration of multiple components are evaluated, with the result showing significant differences from those based on a single fluid approach. This comparison indicates that precise evaluation of the energy and magnetic flux transport of energetic events in the magnetotail requires resolving individual populations in the phase space density.     

An approach to geometric reasoning in robotics

Anticipating the use of knowledge-based expert systems for robot task planning, a geometric reasoning is envisioned for the representation and manipulation of geometric information in a manner uniform with other knowledge. The general requirements for such a reasoner are outlined and a proposed architecture is described, built on four concepts: a class structure of spatial sets, features as subsets of those spatial sets, geometric abstractions as partial representations of features, and constraints as a mechanism for reasoning. An example implementation is built in an object-oriented environment and uses an underlying solids modeler, transparent to the end user     

休闲时代太极拳生存空间的拓展

运用文献资料法、逻辑分析法,从生理学、心理学和美学的角度阐述了太极拳的休闲功能,提出了通过鼓励开发太极拳文化和太极拳衍生项目、积极发展太极拳休闲俱乐部、努力开发太极拳人文景现、加强宣传,树立太极拳休闲品牌来拓展太极拳在休闲时代的生存空间.     

Space Weather in the Equatorial Ionosphere

The ‘scintillations’ observed on signals received in the equatorial region from GPS satellites are due to plasma instabilities in the F region of the ionosphere, also detected as spread F. These instabilities give rise to depletions of ionisation or ‘bubbles’. The occurrence of these events and their relation to the equatorial electrojet are reviewed. Possibilities of short-term forecasting are examined with particular attention to problems encountered in modelling the equatorial electrojet. This revised version was published online in August 2006 with corrections to the Cover Date.     

TWT Reliability in Space

The question of Traveling Wave Tube (TWT) reliability in space poses some unique problems. First, since tube reliability has a tremendous impact on system design and overall cost, if problems do occur, they are highly visible. Second, attaining high reliability is made difficult by small production runs and short delivery schedules. Finally, the now-common 10 year life specification is combined with state-of-the-art performance requirements, forcing design changes and adding risk. To meet these requirements, we emphasize certain design and manufacturing ground rules. When orbital TWT problems do occur, our experience is that they are usually caused by infant mortality, not wearout. Data based on operation in space show that with close attention to the details of design and manufacturing, reliability exceeding the 500,000 hours MTBF normally specified is achieved. Traveling Wave Tube reliability and overall performance have a tremendous impact on system design and the overall cost of a satellite. TWT reliability determines the amount of redundancy needed to meet a given satellite mission objective. Increased redundancy means increased complexity and weight of the spacecraft. The TWTs, with their Electronic Power Conditioners, also dissipate over 80% of all spacecraft power. Increased tube efficiency will therefore simplify matters all around. Because of the critical impact of tubes, if technical problems do occur, they are highly visible at the system level, where rumors of failure spread like wildfire in the fairly small space community. Attaining high reliability is difficult because of the many conflicting requirements.     

美军加大未来航天装备投资力度

美国军方认为,"如果没有航天部队或者军事航天力量,就根本谈不上加强全球的战略稳定".航天力量建设业已成为美军信息化建设的新重点.根据美国防部近期制定的《2006～2011财年未来防御计划》(FYDP),2006财年国防部整个航天计划预算将达到223亿美元.     

Execute Command in Space Communications

Two types of feedback systems for a command channel are described. a) Complex Feedback?where, for each command, an identification is relayed back over the feedback channel. b) Decision Feedback?where the feedback channel is used only to state whether the satellite recognized the transmission as a command word. For a), the decision as to whether a command was properly received at the satellite is made on the ground, while for b), the decision is made at the satellite, the only purpose of the feedback channel being to cause the ground station to retransmit the command word if the satellite did not recognize the initial transmission. The decision feedback system then amounts to a one-way channel, since the satellite makes a decision after the initial transmission as to whether or not a command word was sent. If the transmitted command word is interpreted as a command, whether correct or not, the ground station has no further control. The following theorem is proved rigorously: ``It is always possible to specify a decision feedback system which gives the same error performance as a given complex feedback system.'     

Project Space Vision in retrospective

Project Space Vision aimed to influence long-term space policy-makers through documenting visions and fundamental priorities, as seen through the eyes of the post-Apollo generation, for the coming 50 years of space activities. Within a strict thirty-day project time limit, several thousand potential target contributors were addressed using the Internet. Within a few weeks time, resulting inputs were received internationally from young professionals linked to space to form the basis of the final analysis. The results fundamentally showed that some historically driving motivations, such as national security, prestige and technology development, were not well supported as major rationale for space activities. General misconceptions regarding the magnitude of space expenditures were further highlighted. Together with identification of the main perceived barriers for progress and specific priorities in more detailed areas, a set of basic components of a fundamental space policy for the future were eventually formulated     

太空旋游不是梦——世界上第一个私营空间站计划出台

总部设在荷兰的和平公司于2001年9月4日宣布，它已就世界上首座私营空间站的设计、研制、发射和使用问题同俄罗斯有关方面达成了一项历史性的协议。在协议上签字的有俄航空航……     

Space propulsion: the antimatter advantage

It is suggested that, based upon current research, there exist several possibilities for future propulsion techniques. Some of the most promising research deals with antimatter and its usefulness in energy production. The potential of antimatter as an efficient and renewable energy source is discussed. The design of an antimatter propulsion system is described     

Space operations and the human factor

The effects of human error on aviation and space flight are discussed and the role of human factor engineering in aviation and aerospace safety is examined. Specific areas discussed are docking and extravehicular activity; quantification of human capacity for space station design; and measurement of habitability, workload, and task analysis.     

Communications satellite technology and services for the 90's

The history of satellite communications is reviewed, and its future is addressed from the viewpoint of both commercial and military users. Technological advances and new services are discussed. User's requirements are assessed     

GE90发动机高压涡轮转叶裂纹问题浅析

介绍了GE90-115B发动机高压涡轮第1级转叶裂纹产生的原因及特点,并结合国航机队运行中的实际故障情况从航线维护检查和车间修理改装两方面对高压涡轮第1级转叶裂纹问题的控制解决措施进行了分析。     

MD90飞机尾段装配的新工艺方法研究

主要分析了在MD90飞机尾段装配过程中的新工艺——销棒压印工艺和要求，以及在有无衬套挤压情况下的使用寿命，论述了通过冷加工方法，在不改变结构件尺寸和不增加重量的前提下，在高应力区对孔壁进行挤胀销棒应力压印，使孔周围材料产生塑性变形，改变应力，并在反复拉伸载荷作用下降低孔边应力峰值，从而提高结构件疲劳寿命。     

载人航天工程空间应用载荷生物安全工程技术体系研究

针对我国载人航天工程空间应用系统科学实验载荷生物危害问题,提出了完整的载人航天工程空间应用科学实验载荷的生物安全工程体系,涉及空间生物安全的定量要求、生物安全等级的划分、生物安全监测以及生物危害的包覆设计等工程范畴。在此基础上,结合我国目前载人空间站空间应用的实际需求,提出了开展空间生物安全防护的工程实践方案和建议,为后续开展载人空间站空间应用系统生物安全设计提供了指导和参考。